This study aimed to investigate the effect of chronic kidney dysfunction (CKD) on the clinical characteristics of patients with acute coronary syndrome (ACS) and the degree of coronary arterial stenosis. The study enrolled 368 patients with ACS who underwent coronary angiography. Blood glucose, glycated haemoglobin (HbA1c), total cholesterol, triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), uric acid (UA), and serum creatinine were examined randomly, and the severity of coronary artery lesions was assessed using the Gensini score. Patients were divided into three groups according to estimated glomerular filtration rate: normal renal function (n = 102), mild renal insufficiency (n = 198), and moderate to severe renal dysfunction (n = 68). The characteristics of patients with coronary artery lesions in the three groups were analysed. Of all patients, 27.7% had normal renal function. In the moderate to severe renal dysfunction group, the majority of patients were women whose average age was older. The ratio of patients with history of hypertension and diabetes mellitus was higher, blood glucose, HbA1c, TG, UA and Gensini score were obviously increased, while HDL-C was significantly decreased; all differences had statistical significance (p < 0.05). Different degrees of CKD occur in patients with ACS. In patients with ACS and CKD, metabolism of glucose and fat are significantly abnormal, and coronary arterial lesions are more serious.